The present invention relates, generally, to cooling devices, and, specifically, to a system for active cooling of electronic devices.
Electronic devices such as computing systems and lighting systems typically include heat generating elements like integrated circuits (ICs), semiconductor components, electrical connections, and light emitting diodes (LEDs) that lead to device heating. Light emitting diodes, on account of the power provided to them, tend to heat up and dissipate heat to their surroundings. The heat generated in LEDs as well as ICs can lead to significant reduction in the operational efficiency and even deterioration of the devices if not addressed. To avoid these problems, many electronic devices are fitted with cooling devices.
Many electronic devices currently employ electric fans that operate periodically to cool the heat generating elements. The electric fans are typically large and require a large amount of power to aide cooling. The size of electric fans increases the size of the devices and thus leads to increase in weight. Also, energy efficiency of the devices employing fans is reduced to a great extent since the electric fans consume large amount of power. Electric fans also cannot be fitted in small sized electronic devices. Electronic devices also implement coolant based systems that cause a coolant to flow in the proximity of the heat generating elements to draw the heat away from the device. The coolants used in such cooling systems needs to be changed periodically. Moreover, spillage of the coolant on components in the electronic devices may lead to malfunction of the electronic devices.
Manufacturers have sought to solve the problem of electric fans and coolant based systems with the help of synthetic jets. Synthetic jets typically comprise two plates that form a fluid housing. When the plates are moved back and forth from their original position, ambient air enters the fluid housing and also leaves the fluid housing. At least one of the two plates has apertures to allow for fluids to enter and exit the fluid housing. The plates are fitted with linear actuators to cause the back and forth movement of the plates required for entry and exit of fluid. Linear actuators fixed with the plates of synthetic jets typically comprise pistons, motors and similar devices. Piezoelectric transducers are extensively used to generate motion of the plates in synthetic jets owing to their property of converting electric signals to mechanical vibrations. In many current synthetic jets, at least one plate includes a piezoelectric transducer that is connected to a power source. When an electric signal is provided to the piezoelectric transducer, the plate with the transducer moves away from the rest of the jet assembly thereby increasing the volume of the fluid housing. The increase in volume leads to suction of air into the fluid housing through the apertures on the plate. When the electric signal is disconnected or when a rapidly changing alternating electric signal is applied, the piezoelectric transducer returns to its normal position, thus leading to a reduction in volume of the fluid housing. The reduction in volume leads to a release of air from the apertures, which cools the components of the electronic device that are proximate to the synthetic jets. In some synthetic jets, only one of the plates that form the fluid housing is a piezoelectric disc that deforms on application of electric signal.
Piezoelectric transducers or discs, however, only provide limited displacement of the plates and hence lead to very little release of cooling fluid on the components. In current electronic devices that include many heat-producing components, it is necessary to include multiple synthetic jet assemblies to cool all the components. The increase in number of synthetic jets also leads to an increase in the overall size of the electronic device. Further, most of the current piezoelectric transducer based synthetic jets have shown peak efficiency when the frequency of electric signals supplied to the transducer is greater than 100 Hz. To provide electric signals at such frequencies, power conversion electronics need to be employed. However, the power conversion electronics add to the cost of the cooling system and thus to that of the electronic device.
Thus, there is a need for a system that provides greater displacement of the movable plates without increasing the cost of manufacturing synthetic jets significantly.